School of Agriculture, Policy and Development, University of Reading, Berkshire, UK.
Rothamsted Research, Hertfordshire, UK.
Pest Manag Sci. 2024 May;80(5):2383-2392. doi: 10.1002/ps.7860. Epub 2023 Nov 25.
Current European Union and United Kingdom legislation prohibits the use of neonicotinoid insecticidal seed treatments in oilseed rape (OSR, Brassica napus). This ban, and the reduction in efficacy of pyrethroid insecticide sprays due to resistance, has exacerbated pest pressure from the cabbage stem flea beetle (Psylliodes chrysocephala) in winter OSR. We quantified the direct impact of P. chrysocephala injury on the productivity of OSR. Leaf area was removed from young plants to simulate differing intensities of adult feeding injury alone or in combination with varying larval infestation levels.
OSR can compensate for up to 90% leaf area loss at early growth stages, with no meaningful effect on yield. Significant impacts were observed with high infestations of more than five larvae per plant; plants were shorter, produced fewer flowers and pods, with fewer seeds per pod which had lower oil content and higher glucosinolate content. Such effects were not recorded when five larvae or fewer were present.
These data confirm the yield-limiting potential of the larval stages of P. chrysocephala but suggest that the current action thresholds which trigger insecticide application for both adult and larval stages (25% leaf area loss and five larvae/plant, respectively) are potentially too low as they are below the physiological injury level where plants can fully compensate for damage. Further research in field conditions is needed to define physiological thresholds more accurately as disparity may result in insecticide applications that are unnecessary to protect yield and may in turn exacerbate the development and spread of insecticide resistance in P. chrysocephala. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
目前，欧盟和英国立法禁止在油菜籽（甘蓝型油菜）中使用新烟碱类杀虫剂种子处理剂。由于对拟除虫菊酯杀虫剂喷雾的效果降低，这种禁令加剧了冬季油菜籽中菜心跳蚤的虫害压力。我们量化了菜心跳蚤伤害对油菜籽生产力的直接影响。从小植株上移除叶片面积，单独或结合不同的幼虫侵染水平，模拟不同强度的成虫取食伤害。
油菜籽在早期生长阶段可以补偿高达 90%的叶片损失，对产量没有明显影响。在每株植物有超过 5 条幼虫的高侵染水平下观察到显著影响；植株更矮，花朵和豆荚产量更少，每荚种子更少，含油量更低，硫代葡萄糖苷含量更高。当每株植物有 5 条或更少幼虫时，没有记录到这些影响。
这些数据证实了菜心跳蚤幼虫阶段的潜在产量限制作用，但表明目前触发成虫和幼虫阶段施药的行动阈值（分别为 25%叶片面积损失和每株植物 5 条幼虫）可能太低，因为它们低于植物可以完全补偿损伤的生理损伤水平。需要在田间条件下进行进一步研究，以更准确地定义生理阈值，因为差异可能导致不必要的杀虫剂应用，从而加剧菜心跳蚤中杀虫剂抗性的发展和传播。© 2023 作者。害虫管理科学由 John Wiley & Sons Ltd 代表化学工业协会出版。
